DESCRIPTION: The purpose of this study is to examine the molecular composition of breast fluids for the presence of specific anti- carcinogenic factors. The aims of the proposed study are as follows: 1) Describe repeated measures of the composition of womens' breast fluids post-lactation, including nitrogen, fat, carbohydrates, prolactin and carotenoid; 2) Examine the influence of womens' health factors, such as breastfeeding duration, nutrition, exercise and gravidity on breast fluid compositions; 3) Identify molecular markers for breast cancer in post-lactated breast fluids, including growth factors and growth factor receptors, oncogenes, and tumor suppressor genes in epithelial cell cultures; and 4) Evaluate the relations among gravidity, pre/post-menopausal status, lactation history, nutritional intake, breast cancer risk factors, carotenoid availability, and presence of molecular markers for breast cancer. Women (Caucasian, African-American, and Hispanic) will be recruited for participation by criteria, which includes breast-feeding at least one child for at least 6 months and being totally weaned for at least 3 months (N=100). Women will be asked to complete a health history and demographic questionnaire as well as a diet intake history. Blood for serum prolactin will then be drawn. Breast fluids will be aspirated by subjects every other day, then frozen for later analysis. After a collection period of 17 days, the total sample will be picked-up and blood for a final serum prolactin drawn. A balancing plan will be used to divide the capillary tubes for analysis to control for the influence of expression on the next and subsequent breast fluid sample. The samples will be express-mailed on dry ice to the collaborators for analysis. Questionnaire and assay data will be analyzed with repeated measures MANOVA (for within and between subject/group differences) and regression analyses to predict outcome variables--carotenoid and prolactin levels (MR) and presence of anti-tumor markers/cell dysplasia (LR).